Solvent assisted dyeing of wool fibers with reactive dyes in a ternary solvent system for protecting fibers against damage

Abstract

Severe effluent pollution and chemical damage to protein fibers generated from conventional aqueous dyeing process have stimulated interest in exploiting sustainable dyeing of wool. Herein, an ethanol (EtOH)-carbon tetrachloride (CCl4)-water (H2O) ternary solvent system was used as the dyeing medium to protect wool fibers from being damaged in the dyeing process. The wool fibers were firstly pretreated in an aqueous acid solution, followed by dyeing in the EtOH-CCl4-H2O (45:50:5) ternary solvent system with reactive dyes. The results indicated that the acid pretreatment solution could be reused for several times, the samples dyed in the EtOH-CCl4-H2O mixture with the investigated dyes showed higher K/S values compared to the conventional approach, implying the increased dye utilization and decreased effluents discharge were realized. Furthermore, acceptable permeability, good colorfastness, and satisfactory leveling properties of the dyed samples were achieved using the developed method. Additionally, the solvent-assisted dyed samples showed improved mechanical properties compared with the conventionally dyed samples. The dyeing mechanisms of wool fibers in the EtOH-CCl4-H2O mixture were illustrated in detail. The proposed dyeing technology consumes fewer energy, freshwater, and chemicals compared with the conventional wool dyeing method. Future work will principally concentrate on the reuse of the dye-contaminated EtOH-CCl4-H2O mixture.